Even though some companies have backed off their commitment to renewable energy investments in the past year, that isn't the case at Intel. The U.S. Environmental Protection Agency has just updated its quarterly rankings of the top "green power" purchasers, and the high-tech giant leads heads the national ranking for the fifth straight year.

Between its on-site generation projects, the renewable energy credits (RECs) it buys through Sterling Planet and clean energy it sources from utility company PNM, Intel is driving 3.1 billion kilowatt-hours (kWhs) in green power consumption on an annual basis (or 100 percent of its power needs).

For contest, the Top 50 companies on the EPA's list purchase about 17 billion kWhs combined, about 70 percent of the clean power commitments made through its Green Power Partners program.

The EPA considers green power to be electricity created by solar, biogas, biomass, small-hydro or wind technologies.

The other technology companies on the Top 50 list with Intel are Microsoft (No. 3 with 1.1 billion kWhs, or 46 percent), Cisco Systems (No. 9 with 459 million kWhs, or 44 percent), Sprint (No. 25 with 176 million kWhs, or 5 percent), and Dell (No. 39 with 119.4 kWhs, or 29 percent).